Haw at his Parliament Square camp in 2005. Some saw it as an eyesore and others as an integral patch of democracy. Photograph: Sarah Lee

Brian Haw, who has died aged 62 after being treated for lung cancer, was a tenacious peace campaigner who in 2001 took up residence in Parliament Square, beneath a banner that read "Stop Killing My Kids", and refused to relinquish his patch for nearly 10 years.

Haw travelled from his home in Redditch, Worcestershire, to Westminster on 2 June that year, moved to publicise the effects of British sanctions on Iraq. Days of praying and fasting turned into months of protest as Haw outlasted others who had brought their temporary grievances to the pavement opposite the Houses of Parliament. Soon, he was no longer protesting about sanctions, but against the build-up to the war in Iraq, then the war itself, and the occupation that followed. When he finally left the pavement in March 2011, he was still warning onlookers and passers-by of the effects of the conflicts in Afghanistan and Iraq.

Haw was born in Woodford Green, Essex, and grew up in Whitstable, Kent, where he had his first experiences of an evangelical church at the age of 11. His father, a wartime sniper in the Reconnaissance Corps, had been one of the first to enter the Bergen-Belsen camp after it was liberated and his experiences were partly, Haw said, what led him to take his own life when his son was 13. Haw was apprenticed to a boatbuilder, then joined the merchant navy and eventually saw the Suez Canal and Bombay, "and if those people were here now, they'd say: 'Is all this pavement yours? You're living like a king'," he said in 2002.

His camp at Westminster varied in size over the years and was labelled both an eyesore and an integral patch of democracy. Day after day, it was home to a man whose life was protest, and whose talent was survival in a harsh landscape of exhaust fumes and police scrutiny. Haw spent hours speaking to supporters, detractors and those who stood quietly surveying photos of dead Iraqi children. His battered banners became a visual counterpoint to the usual tourist snaps of Whitehall. Their variety and colourful insistence was not lost on the artist Mark Wallinger, who won the 2007 Turner prize with a piece entitled State Britain, a recreation of Haw's display.

Haw was guided by his fervent Christian beliefs, and aided at times by practical pieces of equipment, including a cheap megaphone. No one who worked in Whitehall, from the prime minister down, could remain unaware of his presence. His shouted slogan, "45 minutes, Mr Bliar", was so loud it led to objections by MPs. In 2002, Westminster city council tried unsuccessfully to remove Haw's camp, but his greatest legal challenge came in 2005 when the Serious Organised Crime and Police Act was passed, banning any public protest within one kilometre of Parliament Square. Particularly troubling for Haw was Section 132, which would allow police to remove any permanent protesters in the square. ("Serious organised crime?" Haw asked. "Do they really think I'm the Godfather?") Haw won an application for judicial review of the act as it required all protests to have authorisation from the police "when the demonstration starts", and his had already been going for a long time. He gained permission to stay, subject to conditions regarding the size of his display.

His closest supporters, who furnished Haw with sandwiches and cigarettes over the years, would class him as another in the line of tenacious Christian protesters bearing witness. Haw himself was puzzled that so few others could spare the time to come to Parliament Square. He saved some anger for those who thought a single march in 2003 would force the government to stop its involvement in Iraq. In his view, if 100,000 people had arrived and refused to move for a week, war would have been averted. It wasn't so hard, Haw said, just to come and sit in front of this place and protest.

Haw was uncomfortable speaking about the practical nature of his life on the pavement. Questions about survival, sleeping habits, showers, the fumes and police presence were often ignored or deflected. Over the years his skin became leathery. His nose was broken twice. The 10 years took their toll, and some questioned whether his protest had become ineffective.

What was impossible to question was Haw's combination of friendliness and bloody-mindedness, his insistence that it was not impossible to be heard, to challenge courts, to remind those in power of the consequences of their actions. Haw angered some, mystified others, and continued to prowl the pavement, even on crutches, wearing a hat covered in badges, with slogans such as "Keep My Muslim Neighbours Safe". Years into the protest, the battered hat looked as if it was more badge than corduroy.

"I don't mind them," Haw said in 2002 when asked about the mice that appeared in the square around dusk. He pointed a finger towards parliament. "It's the rats over there on the other side we have to look out for." Haw was father to seven children with his wife Kay, who divorced him in 2003.

•Brian William Haw, peace campaigner, born 7 January 1949; died 18 June 2011